This is a 3-year prospective study of 800 employees across a variety of industries, occupations and locations to determine the dose-response relationships between exposure to biomechanical factors and the development of hand, wrist, and elbow musculoskeletal disorders (MSDs), such as epicondylitis, wrist tendonitis and carpal tunnel syndrome. Although there is a substantial body of epidemiologic data linking various workplace factors to the development of upper extremity MSDs, the dose-response relationships between biomechanical factors and specific disorders are not well characterized. This data is critical for employers, employees and government agencies in order to establish the most effective prevention strategies. Companies and jobs will be targeted to achieve a distribution of exposure levels to biomechanical risk factors. Generally, stable, monotask jobs will be selected for study. At initial recruitment and then annually the following will be completed for all participants: baseline questionnaire, physical examination focused on the upper extremity, and a job analysis. On a quarterly basis, employees will complete a brief questionnaire and if their reported pain level is above a threshold, the physical exam will be repeated. If the job tasks change the job analysis will be repeated. It is anticipated that approximately 650 employees will be recruited on first site visit with an additional 150 new hires recruited at follow-up visits. The relationships between exposures and the development of specific and pooled musculoskeletal disorders will be examined using a Cox proportional hazards model controlling for historical and significant covariates (e.g., gender, age, psychosocial factors). The data will be evaluated for dose-response and threshold relationships. Participating employees will be notified of physical exam findings and employers and employees will be notified of the final study findings. Study methods, instruments, and data format will be coordinated with the NIOSH Work-related Musculoskeletal Disorders Consortium.